A method is widely known in which acrylonitrile is produced by a vapor phase catalytic ammoxidation reaction using propylene, ammonia, and molecular oxygen (oxygen-containing gas) as a starting material in a fluidized reactor. In particular, a composite oxide catalyst containing iron and antimony is useful in the ammoxidation reaction and industrially widely used.
Hitherto, a large number of researches have been made on the composite oxide catalyst containing iron and antimony and thus various catalysts have been proposed.
For example, a composite oxide catalyst with at least one kind of element selected from the group consisting of iron, antimony, cobalt, and nickel is disclosed in Patent Document 1.
In addition, a composite oxide catalyst containing iron, antimony, tellurium, and further vanadium, molybdenum, tungsten, or the like is disclosed in Patent Documents 2 to 8. Moreover, a method for producing a catalyst containing these iron and antimony is disclosed in Patent Documents 9 to 11.
Furthermore, several proposals have also been made for the method for producing acrylonitrile which can suppress the time course of the catalyst performance and thus maintain a high acrylonitrile yield over a long period of time.
For example, it is specified in Patent Document 12 that the selectivity of the desired product and the catalytic activity are improved by enriching tellurium to the catalyst with decreased performance resulted from the use in a reaction and heating at a high temperature of 900° C. or lower. In addition, it is disclosed that a high acrylonitrile yield is maintained by replacing the catalyst in the reactor with this tellurium enriched catalyst.
In addition, it is disclosed in Patent Document 13 that the selectivity of the desired product and the time dependent decrease in the catalytic activity are improved by adding a tellurium support, a tellurium compound, and a molybdenum compound into the reactor during the ammoxidation reaction using a tellurium-containing oxide catalyst.